As someone who was a private nanny for quite some time, I would recommend an agency. Although you pay more, I think it's important to know that you dont have to 'check' that person out more than in terms of your gut feeling for them - and the Qs you have - because police checks etc etc are already done. Its nice to get someone who has been in the job a while. I know that from my experience only, the younger sole charge nannies were not quite as 'motherly' as the older women, simply because of where they were at in their lives. I saw the occassional younger nanny who was excellent, so you cant tar everyone with the same brush - but I think life experience brings so much to the role of who is caring for your children.

Also - what about Family Day Care. A nice option in that your child would have other children to play with? This is an old post so maybe you have luck by now finding who you need?